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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta name="generator" content="HTML Tidy, see www.w3.org"><meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><link type="text/css" rel="stylesheet" href="style.css"><!-- Generated by The Open Group's rhtm tool v1.2.1 --><!-- Copyright (c) 2001-2003 The Open Group, All Rights Reserved --><title>isalnum</title></head><body bgcolor="white"><script type="text/javascript" language="JavaScript" src="../jscript/codes.js"></script><basefont size="3"> <a name="isalnum"></a> <a name="tag_03_283"></a><!-- isalnum --> <!--header start--><center><font size="2">The Open Group Base Specifications Issue 6<br>IEEE Std 1003.1, 2003 Edition<br>Copyright © 2001-2003 The IEEE and The Open Group, All Rights reserved.</font></center><!--header end--><hr size="2" noshade><h4><a name="tag_03_283_01"></a>NAME</h4><blockquote>isalnum - test for an alphanumeric character</blockquote><h4><a name="tag_03_283_02"></a>SYNOPSIS</h4><blockquote class="synopsis"><p><code><tt>#include <<a href="../basedefs/ctype.h.html">ctype.h</a>><br><br> int isalnum(int</tt> <i>c</i><tt>);<br></tt></code></p></blockquote><h4><a name="tag_03_283_03"></a>DESCRIPTION</h4><blockquote><div class="box"><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]"border="0"> The functionality described on this reference page is aligned with the ISO C standard. Any conflict between therequirements described here and the ISO C standard is unintentional. This volume of IEEE Std 1003.1-2001 defers tothe ISO C standard. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></div><p>The <i>isalnum</i>() function shall test whether <i>c</i> is a character of class <b>alpha</b> or <b>digit</b> in the program'scurrent locale; see the Base Definitions volume of IEEE Std 1003.1-2001, <a href="../basedefs/xbd_chap07.html">Chapter 7,Locale</a>.</p><p>The <i>c</i> argument is an <b>int</b>, the value of which the application shall ensure is representable as an <b>unsignedchar</b> or equal to the value of the macro EOF. If the argument has any other value, the behavior is undefined.</p></blockquote><h4><a name="tag_03_283_04"></a>RETURN VALUE</h4><blockquote><p>The <i>isalnum</i>() function shall return non-zero if <i>c</i> is an alphanumeric character; otherwise, it shall return 0.</p></blockquote><h4><a name="tag_03_283_05"></a>ERRORS</h4><blockquote><p>No errors are defined.</p></blockquote><hr><div class="box"><em>The following sections are informative.</em></div><h4><a name="tag_03_283_06"></a>EXAMPLES</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_283_07"></a>APPLICATION USAGE</h4><blockquote><p>To ensure applications portability, especially across natural languages, only this function and those listed in the SEE ALSOsection should be used for character classification.</p></blockquote><h4><a name="tag_03_283_08"></a>RATIONALE</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_283_09"></a>FUTURE DIRECTIONS</h4><blockquote><p>None.</p></blockquote><h4><a name="tag_03_283_10"></a>SEE ALSO</h4><blockquote><p><a href="isalpha.html"><i>isalpha</i>()</a> , <a href="iscntrl.html"><i>iscntrl</i>()</a> , <a href="isdigit.html"><i>isdigit</i>()</a> , <a href="isgraph.html"><i>isgraph</i>()</a> , <a href="islower.html"><i>islower</i>()</a> ,<a href="isprint.html"><i>isprint</i>()</a> , <a href="ispunct.html"><i>ispunct</i>()</a> , <a href="isspace.html"><i>isspace</i>()</a> , <a href="isupper.html"><i>isupper</i>()</a> , <a href="isxdigit.html"><i>isxdigit</i>()</a> ,<a href="setlocale.html"><i>setlocale</i>()</a> , the Base Definitions volume of IEEE Std 1003.1-2001, <a href="../basedefs/xbd_chap07.html">Chapter 7, Locale</a>, <a href="../basedefs/ctype.h.html"><i><ctype.h></i></a>, <a href="../basedefs/stdio.h.html"><i><stdio.h></i></a></p></blockquote><h4><a name="tag_03_283_11"></a>CHANGE HISTORY</h4><blockquote><p>First released in Issue 1. Derived from Issue 1 of the SVID.</p></blockquote><h4><a name="tag_03_283_12"></a>Issue 6</h4><blockquote><p>The DESCRIPTION is updated to avoid use of the term "must" for application requirements.</p></blockquote><div class="box"><em>End of informative text.</em></div><hr><hr size="2" noshade><center><font size="2"><!--footer start-->UNIX ® is a registered Trademark of The Open Group.<br>POSIX ® is a registered Trademark of The IEEE.<br>[ <a href="../mindex.html">Main Index</a> | <a href="../basedefs/contents.html">XBD</a> | <a href="../utilities/contents.html">XCU</a> | <a href="../functions/contents.html">XSH</a> | <a href="../xrat/contents.html">XRAT</a>]</font></center><!--footer end--><hr size="2" noshade></body></html>⌨️ 快捷键说明
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